Solvation chemistry of rare earth nitrates in carbonate electrolyte for advanced lithium metal batteries

Lithium metal is recognized as the next generation anode material due to its ultra-high capacity. However, the safety hazards caused by the dendritic lithium growth hinder its practical application. In this work, rare earth nitrates, such as Y(NO3)3, are introduced as electrolyte additives because of the unfixed coordination number and complex coordination configuration for rare earth cations. Molecular dynamics simulation reveals that the rare earth ion changes the solvation structure of the lithium ion. When it is combined with fluoroethylene carbonate (FEC), the interphase generated from electrochemical reactions is favorable for the dense Li deposition. As a result, a stable and high Coulombic efficiency is achieved for Li/Cu cells in commercial carbonate electrolyte with such additive. The Li/Li symmetrical cells can operate>1000 h at current density of 1 mA cm−2. Moreover, the NCM811/Li full cells deliver superior cycling stability and better rate performance. This strategy sheds light on utilizing rare earth elements to optimize the electrolyte for lithium metal anode and it can be extended to other electrolytes aiming at sodium and potassium battery chemistry.